Data Management with Spectrum Analyzers

ABSTRACT

A spectrum analyzer contains a number of improvements that adapt it to common commercial uses. The spectrum analyzer is capable of automatically wirelessly receiving and synchronizing frequency spectrum data collected from multiple remote spectrum analyzers with respect to frequency, time and location. A selector function is used to create composite fre quency data set from multiple frequency data sets while allowing retroactive identification and examination of the original frequency data. An improved non-linear graphical display of the frequency spectrum data is created by automatically expanding the resolution of frequency axis for frequency ranges having signals of interest and contracting the resolution of the frequency axis of frequency ranges having no signals of interest.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a divisional of and claims priority fromco-pending U.S. patent application Ser. No. 14/677,167 filed Apr. 2,2015 which claimed priority from co-pending Provisional PatentApplication No. 61/974,190 entitled “Spectrum Analyzer” filed Apr. 2,2014, all of which are hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

REFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING APPENDIX

Not Applicable.

BACKGROUND OF THE INVENTION

Frequency spectrum analyzers are common products with a broad range ofcommercial applications. Examples of such applications include, but arenot limited to, commercial RF technologies such as AM, Cellular, PCS,DCS, 2G, 3G, 4G, LTE, CDMA, cdmaOne, CDMA 2000, W-CDMA/CDMA, 1x EV-DO,DECT phones, GSM, GPRS, EDGE, FM, UMTS, HSDPA, W-CDMA, TDMA, AMPS aswell as 802.11, Bluetooth, Broadcast, Emergency, Fire, GPS, HDTV, IBOC,In-Building, Microwave, NPSPAC, Paging, Police, Private radio, Project25, Public, RADAR, Safety, Telematics, TETRA, Trunking, UMTS, WiMAX,Wi-Fi, WLAN and WLL. Spectrum analyzers are used to perform a widevariety of tasks that can occur in connection with these commercial RFapplications such as installation, maintenance, troubleshooting, antennaalignment, RF measurements for radio and TV broadcasting, mobile phonebase station radiation power density measurements, magnetic interferenceor leakage from motors and/or miscellaneous machinery, testing of wiringfor RF energy, electromagnetic field strength measurement for variousEMC limits, and cellular/cordless phone radiation levels.

Additional examples of the commercial use of spectrum analyzers duringeveryday tasks include searching for unknown RF transmissions, FCCcompliance, monitoring blasting sites, identifying RF interferenceimpacting communications systems, security surveys for corporate boardrooms, VIP protection, protection of intellectual property, detectionand location of magnetic fields, and detection of signal interferenceand undesired RF emissions from medical equipment.

Universities, community colleges, vocational schools, and high schoolsalso use spectrum analyzers for educational labs and research. There isa similar demand from small start-up companies, hobbyists and individualinventors for a low cost spectrum analyzer that they can use indeveloping and exploring new product innovations. Spectrum analyzers arealso often used in the home to address personal living environment RFsafety concerns.

Unfortunately, many currently available spectrum analyzers are veryexpensive, overly complicated to use, primarily adapted to sophisticatedengineering use and generally ill-suited to perform more commoncommercial tasks for which they are commonly used. Therefore, what isneeded is a low cost spectrum analyzer that is easy to use and adaptedto the needs of the commercial user.

Also, there are many applications that would benefit from an in placespectrum analyzer that could be monitored from a remote location. Thisis currently available in many commercial spectrum analyzers using wiredmethods, but it would be beneficial to have a remote spectrum analyzerthat could be monitored using remote wireless means.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed toward improvements in the operationof commercial spectrum analyzers. More particularly, an embodiment ofthe invention is directed toward a method of displaying frequency datafrom multiple data sets or multiple devices in a simple and concisemanner. In accordance with the method, a first set of frequency spectrumdata points is collected with the spectrum analyzer. A second set offrequency spectrum data points is then collected with the spectrumanalyzer. Using the frequency of each data point, the two data sets arealigned so that points from the first data set at each frequency arealigned with points on the second data set that have the same frequency.A selector function is then applied to each of the first set of datapoints and the corresponding second set of data points. The selectorfunction designates either the data point from the first set of data orthe corresponding second set of data. In a preferred embodiment, theselector function designates a data point as a selected data point basedupon which one has the largest signal amplitude. A composite data set ofthe selected data points is formed by retaining the origin of each datapoint in the selected data set. The composite data set is thendisplayed. Using this method, composite data sets can be created frommultiple data sets with the original data sets coming from differentspectrum analyzers or from the same spectrum analyzer taken at differentlocations or different times. Composite data sets can also be createdfrom two or more composite data sets. Each data point in the compositedata set retains the identity of its source data, such that the userwould be able to determine which source data set any point in thecomposite data set came from.

Another embodiment of the present invention is directed toward a methodof operating and monitoring data on a plurality of frequency spectrumanalyzers. In accordance with the method, a computer or spectrumanalyzer is designated as a master controller device. One or morespectrum analyzers are then designated as slave devices and acommunication link is established between the controller device and theslave devices. Frequency spectrum data is then collected with the slavespectrum analyzers and transmitted to the master device. In addition,other types of spectrum analyzer data can also be transmitted such asI&Q data and/or signal list information. The master device displays acomposite data set created from the spectrum data sets from the spectrumanalyzers. The master device can be connected to the slave devices byEthernet or by a proprietary wireless communications protocol. There areinfinite possibilities with regard to wireless protocols but onepossible embodiment of the proprietary wireless standard is based ontraditional Wi-Fi technology which is used to transmit data from theslave devices to the master device using information packets. However,in order to not corrupt the monitored spectrum, the Wi-Fi transmissionis halted while the spectrum analyzers collect spectrum data so that theWi-Fi transmission does not appear in spectrum data. In essence themaster/slave communication must be interleaved and synchronized with thespectrum analyzer sweeping functions so that the spectrum analyzers maymonitor the true frequency spectrum without detecting the master/slavecommunications.

Yet another embodiment of the present invention is directed toward amethod of producing a non-linear frequency display for a frequencyspectrum analyzer. When using a spectrum analyzer to view a widefrequency span, there is often a very large range of frequencies whereno signals exist. A more useful display provides increased visibility ofareas in the frequent spectrum with more densely populated signals whileproviding less visibility for areas of the spectrum where no signalsexist. In accordance with the method, a frequency spectrum trace in aspecified frequency span is captured with a spectrum analyzer. Frequencyranges in the specified frequency span having signal levels or datapoints above a specified amplitude threshold level are then identified.An output display is produced having a frequency axis wherein frequencyranges having a high concentration of signals are graphical expandedmore than frequency ranges not having a high concentration of signals.This algorithm is preferably based on the total RF energy measured overspecified frequency range. Hence, when viewing a large portion of thefrequency spectrum on a spectrum analyzer, the normal frequency spectrumdisplay is replaced with a non-linear frequency spectrum axis displaywhich provides greater visibility of densely populated areas of thefrequency spectrum. When the user zooms in to desired portions of thespectrum, the non-linear display effect can be reduced or completelyremoved so that that power spectral density of individual signals is notdistorted because of the non-linear display effect. This non-lineardisplay effect may be implemented using normal line type graphing, or,in another embodiment, bar graphs may be used to represent the densityof spectrum. In the bar graph embodiment, each bar graph may represent adifferent span of frequency spectrum based on the density of the signalswithin that span with the amplitude of the bar graph representing thepeak or average of the signals within that span. And finally, thenon-linear displays may be used to represent the composite tracespreviously described for an improved method of rapidly viewing thefrequency spectrum generated from multiple data sets.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a system block diagram of a spectrum analyzer constructed inaccordance with an embodiment of the present invention;

FIG. 2 is a block diagram of the logic of the gate array of the spectrumanalyzer of FIG. 1;

FIG. 3 is a block diagram of the receiver 4 of the spectrum analyzer ofFIG. 1;

FIGS. 4(A) and 4(B) are illustrations of the exterior housings ofspectrum analyzers constructed in accordance with preferred embodimentsof the present invention;

FIG. 5 is a flow chart of a wide span sweep mode of operation of aspectrum analyzer constructed in accordance with an embodiment of thepresent invention;

FIG. 6(A) is a flow chart of a non-linear display mode of operation of aspectrum analyzer constructed in accordance with an embodiment of thepresent invention;

FIG. 6(B) is an example of a non-linear display created in accordancewith the method of FIG. 6(A);

FIG. 7 (A) is a flow chart of a method of combining and organizingmultiple sets of frequency data into a single composite data set fordisplay in accordance with an embodiment of the present invention;

FIG. 7(B) is an example of how points in a composite data set created inaccordance with the method of FIG. 7(A) may be indexed;

FIG. 7(C) is an example of a composite data set created in accordancewith the method of FIG. 7(A) based on location;

FIG. 7(D) is an example of a composite data set created in accordancewith the method of FIG. 7(A) based on time;

FIG. 8 is a flow chart of a signal inspection mode of operation of aspectrum analyzer constructed in accordance with embodiment of thepresent invention; and

FIG. 9 is a flow chart of a controller mode of operation of a spectrumanalyze constructed in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, a system block diagram of the electricalcomponents of a spectrum analyzer 2 constructed in accordance withembodiment of the present invention is shown. The main components are areceiver 4 that receives and processes signals from the environment anda field programmable gate array 6 with an internal processor thatperforms the required processing and manages the various components ofthe analyzer.

The receiver 4 detects the signals received by the antenna 5 of thespectrum analyzer 2. The output of the receiver 4 is digitized by adigital to analog converter 8 and read by the field programmable gatearray 6. A wireless transceiver and GPS circuitry 24 connected to thegate array 6 provides the analyzer 2 with digital communication andlocation capabilities. The GPS transceiver module 24 is beneficial inthat it allows the spectrum analyzer 2 to store location informationalong with the associated frequency data.

The gate array 6 controls an LCD Display 36, a USB port 38 for thepurpose of connecting storage, operating system memory 44, internalmemory 48 and Ethernet circuitry 46. A haptic feedback motor 42 undercontrol of the gate array 6 provides tactile feedback through vibration.An analog to digital converter 26 is used to connect the gate array 6 toseries of audio input/outputs including a microphone 28 and audio injack 30. An audio out jack 32 and speaker 34 connect directly to thegate array 6. Power 50 and clock signal 52 circuits are connected to thegate array 6 to power and synchronize the circuitry of the analyzer 2.

The field programmable gate array 6 is connected to an accessory jack 20that is used to couple the analyzer 2 to attachable accessories 22 suchas a magnetic field sensor, acoustic sensors, RF broadband power meteror visible or infrared light sensors. A magnetic field sensor allows theanalyzer to be used to monitor magnetic interference or leakage frommotors, generators, or misc. machinery. Light transmissions are detectedthrough light meters and light probes that can be attached to the deviceas accessories. Accessories are also provided for the measurement anddetection of acoustic or ultrasonic mechanical vibrations and thetesting of wiring for acoustic or RF energy. These accessories can beeasily coupled to the device through the accessory jack 20 or otherinput/output ports.

Referring now to FIG. 2, a block diagram of the signal processing of thespectrum analyzer of FIG. 1 is shown. The digitized signal from theanalog to digital converter 8 is processed in a data acquisition buffer72. A window function 74 is used to limit the frequency span of thedata. A Fast Fourier Transform 76 is performed on the frequency data inthe selected window. Combining and performing overlap correction 78 isperformed on the multiple spectrums produced from each instantaneousblock of frequency and spectral data power levels are calculated andwritten to memory 80 for display. The spectral data may be displayedwith a non-linear frequency axis to enhance viewing of densely populatedareas of the spectrum 82.

The raw signal data from the analog to digital converter is also used toproduce an audio output 84. The gate array includes circuitry 86 thatcaptures and saves the raw frequency data and transformed audio or videodata used to produce the audio or video output 86.

FIG. 3 is a block diagram of the receiver 4 of the spectrum analyzer ofFIG. 1. The spectrum analyzer typically contains receiver hardware tocover a broad frequency range typically greater than 1 GHz and hasvarious related probes and antennas that can be connected to thereceiver input circuitry 100. The front end circuitry contains areceiver that is capable of down-converting portions of the frequencyspectrum to an (IF) intermediate frequency. The IF bandwidth determinesthe maximum instantaneous frequency bandwidth that the receiver iscapable of processing at an instance in time. The output of the IFbandwidth filter is then sampled using an analog to digital converterand the remaining analysis is done using digital processing techniques.In the embodiment of this invention, the receiver includes a doublesuper-heterodyne receiver path 102 that down converts frequencies in therange from 10 kHz to 6 GHz to an intermediate frequency with a bandwidthof 25 MHz. The output of the receiver 106 is an IF signal that getssampled by an a analog to digital converter and provided to the gatearray of the analyzer, where a Fast Fourier Transform is performed onthe data to produce an output frequency spectrum. For broadbandsweeping, the frequency resolution is preferably fixed so thatstandardized data files can be compared using the same frequencyresolution.

Referring now to FIGS. 4(A) and 4(B), illustrations of the exteriorhousings of two preferred spectrum analyzer 110 and 112 constructed inaccordance with preferred embodiments of the present invention areshown. The analyzer 110 shown in FIG. 4(A) is a small hand held batterypowered device with a 5 inch touch screen display 114. The model 112shown in FIG. 4(B) has a larger display 116 and includes the capabilityto be controlled by a computer either through a wireless or Ethernetconnection. While the housings shown in FIGS. 4(A) and (B) arepreferred, those skilled in the art will appreciate that the presentinvention could be embodied in a wide variety of designs.

Once the analyzers have recorded spectrum data, the analyzer units canbe used to process and manipulate the stored data through a menu drivendisplay. A signal list of detected signals is accessible through menusas well as trace file management functions to store, combine, merge,compare, edit, and manipulate spectrum trace files. Trace math functionscan be selected to add, subtract, average, and apply math functions tothe saved spectrum trace files. A screenshot capture mode is provided.Frequency and power measurement recording capability is available in theform of a single trace and recorded power measurement.

The analyzers preferably have software that provides for automaticidentification of common commercial broadcast protocols such as Wi-Fi,Bluetooth, CDMA, 3G, LTE, etc. based on frequency spectrum, data rates,modulation formats, and other identifying characteristics. In addition,the analyzer units provide basic demodulation of AM and FM signals. Anoscilloscope functionality and view is preferably available whenever theunit is zoomed to a desired frequency span within the instantaneousbandwidth of the receiver and the user has initiated audio demodulation.The units can also record short snippets of demodulated analog audio intheir memory.

A spectrum analyzer of the present invention is preferably capable ofoperating in a number of different modes including a wide span sweepmode. In wide span sweep mode, the analyzer is used in a manner similarto a near field detector, by walking around an area looking at changesin the display to detect RF energy. The emphasis on this mode is forquick detection without providing detailed frequency or powerinformation. In this mode, the display RF graph represents average orpeak RF energy over a broad frequency span depending on the viewedfrequency span and the graph resolution.

Referring now to FIG. 5, a flow chart of the wide span sweep mode ofoperation of a spectrum analyzer constructed in accordance with anembodiment of the present invention is shown. The method begins in step130 with the selecting of a frequency range that is greater than thereceiver instantaneous bandwidth. The analog receiver must scan thisrange by moving the front end analog receiver in fixed blocks that areequal to or less than the instantaneous bandwidth. In step 132, theanalyzer samples and processes the time data within a singleinstantaneous bandwidth block of frequency to form a frequency spectrumof that block of frequency. The method finishes in step 134 with thecombining of the frequency spectrums from multiple instantaneous blocksand the displaying of a graph of the resulting frequency spectrum data.As a result of the sampling time, instantaneous frequency bandwidthblock size, and the wide span sweep mode sweeping function, the unit isnot capable of providing real-time spectrum analyzer data for frequencyspans greater than the instantaneous bandwidth. Details of the spectrumprocessing and the display update are a function of the frequency spanand details are preferably provided below the displayed graph. Thegraphics display preferably incorporates a persistence type display toindicate continuous signals that maybe masked by ambient time changingmodulations.

The spectrum analyzer of this embodiment is also capable of operating ina wide span sweep detector mode of operation. The purpose of the widespan sweep detector mode is to provide the user with a quick assessmentof the RF environment. In wide span sweep detector mode, the analyzer issweeping a broad frequency range between 10 KHz and 6 GHz while thedisplay shows a series of coarse bar graphs, preferably up to about 50.This graphic display depicts the RF energy across the viewed frequencyspan.

The graphic display preferably incorporates non-linear graphictechniques when displaying the frequency axis to provide a more userfriendly view of the RF spectrum over a broad range. Typically, aspectrum analyzer will scan a wide frequency range that will have veryfew signals to display for large portions of the spectrum. The presentinvention preferably utilizes an algorithm to dynamically adjust thedisplayed frequency axis to graphically expand the frequency axis inareas with higher concentrations of signals (RF power) and a graphicallycondensed frequency axis for frequency ranges with little or nomeasurable RF energy.

Referring now to FIG. 6(A), a flow chart of the non-linear display modeof operation of a spectrum analyzer constructed in accordance with anembodiment of the present invention is shown. The method begins in step140 with the sweeping of a broad frequency spectrum. In step 142,frequency ranges having a high concentration of signals are identifiedby observing RF power levels in these ranges. In step, 144, theidentified frequency ranges with higher RF power are then automaticallyexpanded based on total RF energy within the range and any frequencyranges having no signals of interested (low RF power) are contracted.Finally, the frequency spectrum having a non-linear adjusted frequencyaxis is displayed for use by an operator of the analyzer as shown instep 146. An example 147 of a non-linear display created in accordancewith the method of FIG. 6(A) is shown in FIG. 6(B).

In accordance with this type of display system, the horizontal axis isnon-linear, which provides a big advantage for viewing signals with asmall spectral display. As the user “zooms” into the smaller frequencyspans, and the signals of interest expand with respect to the narrowerdisplayed axis, the non-linear display effect is reduced proportionallyto the point that the display is linear below a determined or specifiedfrequency span.

The present inventors have also developed a method of analyzing multiplespectrum traces from different times or locations. Referring now to FIG.7(A), a method of combining and organizing multiple sets of data such asspectrum traces or time series data into a single composite data set fordisplay is shown. The method begins in step 150 with the collecting ofmultiple frequency spectrum data sets from a number of different timesand/or locations. Each data set is then assigned an identificationnumber in step 151. In step 152, the data points of user selected datasets are aligned with respect to frequency. At each aligned index point,the data points for each data set are passed into a selector function asshown in step 153. The selector function returns a chosen data point andthe identification number of the set that contains the data point basedupon which one has the largest signal amplitude. In step 154, a newcomposite data set is created from the original set of data sets and theset of selected data points and set identification number pairs. Thecomposite data set can then be displayed or manipulated as a single setof data, as shown in step 155 while allowing the original source datasets for each composite data value to be identified if desired as shownin step 156. An example 157 of the formation of such a composite traceis shown in FIG. 7(B). An example 158 of the formation of a locationbased composite data set is shown in FIG. 7(B). FIG. (7D) is an example159 of the formation of a time based composite data set. Those skilledin the art will appreciate that the examples of FIGS. 7(A-C) areexemplary only and the actual data arrangements will depend upon theparticular application.

A composite data set can be further composited to form a hierarchaltree-based structure where each node of the tree is a composite set andits set of sequences are branches. From the root composite set, it ispossible to determine the original set for each value by traversing theselected data point/sequence identification number pairs through theircorresponding sub-sequence until reaching a leaf node.

Referring now to FIG. 8, a flow chart of a signal inspection mode ofoperation of a spectrum analyzer constructed in accordance with anembodiment of the present invention is shown. In signal inspection mode,the receiver is tuned to a selected span less than the instantaneousbandwidth of the receiver, step 160, the span is sampled and processed,step 162, and a spectral display is provided to the user in step 164. Insignal inspection mode, the RF spectrum trace is displayed as a lineargraph in a manner similar to a typical spectrum analyzer display.

A current trace, peak trace, average trace, persistence trace, audiodemodulation, oscilloscope view, RSSI function, and spectrogram arepreferably available for selection by the user in signal inspection modeas shown in step 166. When using the product as a stand-alone devicesuch that it is not communicating with any other hardware, a spectrogramfunction is available in all modes. The spectrogram is a quick way toobserve the RF spectrum over a period of time and easily identifyintermittent transmissions while walking around an area. The spectrogramupdate rate may be user definable depending on the receiver scan speedand the processing capability. The spectrogram is a visualrepresentation of the spectrum monitored by the device as it varies withtime but is limited by the sampling duty cycles as described herein.Depending on the operating mode of the analyzer, the spectrogram may bestored at display resolution or at a minimum frequency resolution. Alimited amount of data is buffered depending upon the amount ofavailable memory. User selected spectrograms can be saved to externalmemory as desired. The persistence type display is helpful inidentifying continuous signals that may be masked by ambient timechanging modulations.

The main purpose of the signal inspection mode is to provide a spectrumanalyzer view of the RF power spectral density of a signal. When desiredfor compliance and/or cost reasons, the sweeping function may beimplemented such that the device is not capable of functioning as areal-time spectrum analyzer even when sweeping a single frequency block.Due to the limited bandwidth and sampling time, the duty cycle in suchan embodiment may vary.

The spectrum analyzer may be connected to a PC computer or other centralmaster device via wired or wireless means to operate in a controllermode. In controller mode, the individual analyzer units providefrequency and power information to a central controller device such as aPC or a designated spectrum analyzer unit which is capable of displayingfrequency and power information from multiple units. Applicationsoftware on the master controller captures data from the individualunits. In essence, the controller mode enables “master/slave” operationwhereby a computer or a designated analyzer unit serves as the mastercontroller for multiple analyzer units. The master controller unitpreferably synchronizes the sweeps from multiple units so thatcomparisons can be made from multiple units within a very accurate timeframe. This is especially important when analyzing time changingmodulations.

Referring now to FIG. 9, a flow chart of a master controller mode ofoperation of a spectrum analyzer constructed in accordance with anembodiment of the present invention is shown. The controller mode ofoperation begins in step 180 with the positioning of analyzers atmultiple selected monitoring locations. In step 182, the remoteanalyzers are wirelessly connected to a master controller. While awireless method of connection is preferred, those skilled in the artwill appreciate that dedicated wiring can be used if desired. In step184, the remote analyzers are synchronized with the master controllerand, in step 186, synchronized frequency and power data is collectedwith the remote analyzers. In step 188, the frequency and power datafrom the remote analyzers is transmitted to the master controller. Themethod ends in step 190 with the provision of centralized access to thesynchronized frequency and power data.

The controller mode of operation is intended to provide RF power levelcomparisons from different locations and remote sensors. Thus, thecontroller mode of operation is particularly useful when combined with awireless communication technology such as Wi-Fi or Bluetooth. Using awireless method of communication, the user can quickly go into anenvironment and place units at desired locations without the need to runwires or set up a communication network. When implemented in a wirelessfashion, as a result of data transfer limitations, the remote analyzerunits may be capable of processing sweep traces at a much faster ratethan they can actually transfer data to the master controller.Therefore, in such situations, more detailed trace data may be stored atthe individual analyzer units and, at the request of the mastercontroller, additional detail or resolution may be transferred to thecontroller. Furthermore, each spectrum analyzer unit may function as arepeater for communications from other units. Therefore, a mesh radioapproach may be used to transmit data from a distant unit back to themain controller by relaying the data through a series of slave units.Thus, the central master controller is able to display spectrum analyzertype information from multiple analyzer units spread over a large areawithout the need for increased communications transmit power.

When using the analyzers in a control mode of operation with analyzersconnected to other external hardware such as a PC or spectrum analyzer,the analyzers are able to provide single peak trace updates to theconnected hardware, with finer resolutions achievable for narrowerresolution bandwidths. It is important to note that spectrum analyzersweep duty cycle may be reduced when using wireless means of controllingthe remote units. The primary reason for this limitation is that theanalyzer receiver is not sweeping during the transmission of wirelessdata to the master controller. In the controller mode of operation, thePC or other connected hardware can build a spectrogram or waterfallimage using these single traces received at time intervals from one ormultiple devices. The spectrogram is a visual representation of thespectrum monitored by the device as it varies with time, but can belimited by the time and data constraints as described herein.

The analyzer units preferably have a capability to record I&Q data, orchanges in signal magnitude and phase, over time. This I&Q recordingtime is limited to the instantaneous bandwidth of the unit. At fullinstantaneous bandwidth, the analyzers will have a recording timecapability based on available memory and data recording rate. Fornarrower bandwidths, the recording time will increase proportionally.This recording limitation can be implemented by internal hardware andfirmware to limit the product to commercial applications and render themsubstantially useless for intelligence and/or counter intelligenceapplications. The purpose of the recording function is to be able tocapture a brief sample of a detected RF signal for further analysis andidentification and to provide basic commercial signal identificationfunctions without enabling intelligence gathering. Application softwareis also used to implement functions such as spectrum mask and triggeralert modes to provide warnings when RF levels exceed selectedthresholds. These trigger alerts may be used to store a frequency andpower trace, or initiate I&Q recording.

Although there have been described particular embodiments of the presentinvention of Improved Data Management with Spectrum Analyzers, it is notintended that such references be construed as limitations upon the scopeof this invention except as set forth in the following claims.

What is claimed is:
 1. A method of displaying collected spectrumanalyzer data, said method comprising: identifying a frequency spectrumspan from the spectrum analyzer data; identifying frequency ranges insaid identified frequency span having a high concentration of signals;and producing an output graphical display having a frequency axiswherein frequency ranges having a high concentration of signals aregraphically expanded and displayed while frequency ranges having a lowerconcentration of signals are graphically condensed.